@Beta public abstract class AbstractExecutionThreadService extends Object implements Service
startUp()
, run()
and
shutDown()
methods. This class uses a single thread to execute the
service; consider AbstractService
if you would like to manage any
threading manually.Service.State
Constructor and Description |
---|
AbstractExecutionThreadService() |
Modifier and Type | Method and Description |
---|---|
protected Executor |
executor()
Returns the
Executor that will be used to run this service. |
protected String |
getServiceName()
Returns the name of this service.
|
boolean |
isRunning()
Returns
true if this service is running. |
protected abstract void |
run()
Run the service.
|
protected void |
shutDown()
Stop the service.
|
ListenableFuture<Service.State> |
start()
If the service state is
Service.State.NEW , this initiates service startup
and returns immediately. |
Service.State |
startAndWait()
Initiates service startup (if necessary), returning once the service has
finished starting.
|
protected void |
startUp()
Start the service.
|
Service.State |
state()
Returns the lifecycle state of the service.
|
ListenableFuture<Service.State> |
stop()
|
Service.State |
stopAndWait()
Initiates service shutdown (if necessary), returning once the service has
finished stopping.
|
String |
toString() |
protected void |
triggerShutdown()
Invoked to request the service to stop.
|
protected void startUp() throws Exception
Exception
protected abstract void run() throws Exception
public void run() {
while (isRunning()
) {
// perform a unit of work
}
}
...or you could respond to stop requests by implementing triggerShutdown()
, which should cause run()
to return.Exception
protected void shutDown() throws Exception
Exception
protected void triggerShutdown()
protected Executor executor()
Executor
that will be used to run this service.
Subclasses may override this method to use a custom Executor
, which
may configure its worker thread with a specific name, thread group or
priority. The returned executor's execute()
method is called when this service is started, and should return
promptly.
The default implementation returns a new Executor
that sets the
name of its threads to the string returned by getServiceName()
public final ListenableFuture<Service.State> start()
Service
Service.State.NEW
, this initiates service startup
and returns immediately. If the service has already been started, this
method returns immediately without taking action. A stopped service may not
be restarted.start
in interface Service
Future.get()
will block
until the service has finished starting, and returns one of Service.State.RUNNING
, Service.State.STOPPING
or Service.State.TERMINATED
. If
the service fails to start, Future.get()
will throw an
ExecutionException
, and the service's state will be Service.State.FAILED
. If it has already finished starting, Future.get()
returns immediately. Cancelling this future has
no effect on the service.public final Service.State startAndWait()
Service
start().get()
, this method throws
no checked exceptions, and it cannot be interrupted.startAndWait
in interface Service
public final boolean isRunning()
Service
true
if this service is running.public final Service.State state()
Service
public final ListenableFuture<Service.State> stop()
Service
stop
in interface Service
Future.get()
will block
until the service has finished shutting down, and either returns
Service.State.TERMINATED
or throws an ExecutionException
. If
it has already finished stopping, Future.get()
returns
immediately. Cancelling this future has no effect on the service.public final Service.State stopAndWait()
Service
Service.State.STARTING
, startup will be
cancelled. If this is Service.State.NEW
, it is terminated
without having been started nor stopped. Unlike calling stop().get()
, this method throws no checked exceptions.stopAndWait
in interface Service
protected String getServiceName()
AbstractExecutionThreadService
may include the name
in debugging output.
Subclasses may override this method.
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